1. Field of the Invention
The invention relates to a method and device for wet treating a plate-like article.
2. Description of Related Art
Devices for wet processing of single semiconductor wafers typically include a spin chuck for holding a wafer and rotating it as process liquids are applied to an upper surface thereof. An example of such a device is described in U.S. Pat. No. 4,903,717.
During single wafer processing, as a wafer is treated with one side thereof facing upwardly, residues can build up on the peripheral edge of the downwardly-facing wafer side. These residual build-ups can be removed by use of a suitable chemistry or deionized water (DI) on the unprocessed wafer side. However, for device performance reasons, some applications require that no chemistry or DI should contact the unprocessed wafer side. This is particularly the case when the upwardly facing processed side is the underside of the wafer, whereas the downwardly-facing unprocessed side is the device side of the wafer.
U.S. Pat. No. 6,220,771 describes a device for backside protection of a wafer; however that device requires incorporating into the structure of the chuck a stationary annular seat provided with slant nozzles for supplying protection liquid to a water guard ring formed in the underside of the chuck, from which the protection liquid is supplied to the wafer backside through further slant bores that traverse the chuck at every six degrees about its circumference. This solution therefore requires extensive additional structure as well as modifications to the chuck body that could compromise its structural integrity.
U.S. Patent Pub. No. 2008/0293253 describes a device for wet etching the edge and bevel of a wafer, in which an outer channel applies etching liquid to the periphery of the downwardly-facing wafer side, and a concentric inner channel separated from the outer channel supplies gas to the adjacent inner surface of the channel. In this device, however, the etching liquid is in continuous contact with the wafer underside and dedicated venting must be provided for the nitrogen gas flow.
Improved methods and apparatus for removing residues from a peripheral region of one side of a wafer, while not wetting more central areas of that wafer side, would therefore meet a need in this field.